/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.web;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.xml.XmlEscapers;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.ChecksumException;
import com.google.zxing.DecodeHintType;
import com.google.zxing.FormatException;
import com.google.zxing.LuminanceSource;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.NotFoundException;
import com.google.zxing.Reader;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.client.j2se.ImageReader;
import com.google.zxing.client.result.ParsedResult;
import com.google.zxing.client.result.ResultParser;
import com.google.zxing.common.GlobalHistogramBinarizer;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.multi.GenericMultipleBarcodeReader;
import com.google.zxing.multi.MultipleBarcodeReader;

import com.google.common.io.Resources;
import com.google.common.net.HttpHeaders;
import com.google.common.net.MediaType;
import com.jhlabs.image.GaussianFilter;
import com.jhlabs.image.SharpenFilter;
import com.lucy.model.QRRes;

import java.awt.color.CMMException;
import java.awt.image.BufferedImage;
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumMap;
import java.util.EnumSet;
import java.util.Locale;
import java.util.Map;
import java.util.ResourceBundle;
import java.util.Timer;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.imageio.ImageIO;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

/**
 * {@link HttpServlet} which decodes images containing barcodes. Given a URL, it will
 * retrieve the image and decode it. It can also process image files uploaded via POST.
 *
 * @author Sean Owen
 */
@MultipartConfig(
        maxFileSize = 1L << 26, // ~64MB
        maxRequestSize = 1L << 26, // ~64MB
        fileSizeThreshold = 1 << 23, // ~8MB
        location = "/tmp")
@WebServlet(value = "/w/decode", loadOnStartup = 1)
public final class DecodeServlet extends HttpServlet {

    private static final Logger log = Logger.getLogger(DecodeServlet.class.getName());

    // No real reason to let people upload more than ~64MB
    private static final long MAX_IMAGE_SIZE = 1L << 26;
    // No real reason to deal with more than ~32 megapixels
    private static final int MAX_PIXELS = 1 << 25;
    private static final byte[] REMAINDER_BUFFER = new byte[1 << 16];
    private static final Map<DecodeHintType, Object> HINTS;
    private static final Map<DecodeHintType, Object> HINTS_PURE;

    static {
        HINTS = new EnumMap<>(DecodeHintType.class);
        HINTS.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);
        HINTS.put(DecodeHintType.POSSIBLE_FORMATS, EnumSet.allOf(BarcodeFormat.class));
        HINTS_PURE = new EnumMap<>(HINTS);
        HINTS_PURE.put(DecodeHintType.PURE_BARCODE, Boolean.TRUE);
    }

    private Iterable<String> blockedURLSubstrings;
    private Timer timer;
    private DoSTracker destHostTracker;

    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        Logger logger = Logger.getLogger("com.google.zxing");
        ServletContext context = servletConfig.getServletContext();
        logger.addHandler(new ServletContextLogHandler(context));

        URL blockURL = context.getClassLoader().getResource("/private/uri-block-substrings.txt");
        if (blockURL == null) {
            blockedURLSubstrings = Collections.emptyList();
        } else {
            try {
                blockedURLSubstrings = Resources.readLines(blockURL, StandardCharsets.UTF_8);
            } catch (IOException ioe) {
                throw new ServletException(ioe);
            }
            log.info("Blocking URIs containing: " + blockedURLSubstrings);
        }

        timer = new Timer("DecodeServlet");
        destHostTracker = new DoSTracker(timer, 500, TimeUnit.MILLISECONDS.convert(5, TimeUnit.MINUTES), 10_000);
    }

    @Override
    public void destroy() {
        if (timer != null) {
            timer.cancel();
        }
    }

    @Override
    protected void doGet(HttpServletRequest request,
                         HttpServletResponse response) throws ServletException, IOException {

        String imageURIString = request.getParameter("u");
        if (imageURIString == null || imageURIString.isEmpty()) {
            log.info("URI was empty");
            errorResponse(request, response, "badurl");
            return;
        }

        imageURIString = imageURIString.trim();
        for (CharSequence substring : blockedURLSubstrings) {
            if (imageURIString.contains(substring)) {
                log.info("Disallowed URI " + imageURIString);
                errorResponse(request, response, "badurl");
                return;
            }
        }

        URI imageURI;
        try {
            imageURI = new URI(imageURIString);
            // Assume http: if not specified
            if (imageURI.getScheme() == null) {
                imageURI = new URI("http://" + imageURIString);
            }
        } catch (URISyntaxException e) {
            log.info("Error " + e + " while parsing URI: " + imageURIString);
            errorResponse(request, response, "badurl");
            return;
        }

        // Shortcut for data URI
        if ("data".equals(imageURI.getScheme())) {
            BufferedImage image = null;
            try {
                image = ImageReader.readDataURIImage(imageURI);
            } catch (IOException | IllegalStateException e) {
                log.info("Error " + e + " while reading data URI: " + imageURIString);
                errorResponse(request, response, "badurl");
            }
            if (image == null) {
                log.info("Couldn't read data URI: " + imageURIString);
                errorResponse(request, response, "badimage");
                return;
            }
            try {
                processImage(image, request, response);
            } finally {
                image.flush();
            }
            return;
        }

        URL imageURL;
        try {
            imageURL = imageURI.toURL();
        } catch (MalformedURLException ignored) {
            log.info("URI is not a URL: " + imageURIString);
            errorResponse(request, response, "badurl");
            return;
        }

        String protocol = imageURL.getProtocol();
        if (!"http".equalsIgnoreCase(protocol) && !"https".equalsIgnoreCase(protocol)) {
            log.info("URL protocol was not valid: " + imageURIString);
            errorResponse(request, response, "badurl");
            return;
        }

        if (destHostTracker.isBanned(imageURL.getHost())) {
            log.info("Temporarily not requesting from host: " + imageURIString);
            errorResponse(request, response, "badurl");
        }

        HttpURLConnection connection;
        try {
            connection = (HttpURLConnection) imageURL.openConnection();
        } catch (IllegalArgumentException ignored) {
            log.info("URL could not be opened: " + imageURIString);
            errorResponse(request, response, "badurl");
            return;
        }

        connection.setAllowUserInteraction(false);
        connection.setInstanceFollowRedirects(true);
        connection.setReadTimeout(5000);
        connection.setConnectTimeout(5000);
        connection.setRequestProperty(HttpHeaders.USER_AGENT, "zxing.org");
        connection.setRequestProperty(HttpHeaders.CONNECTION, "close");

        try {
            connection.connect();
        } catch (IOException | IllegalArgumentException e) {
            // Encompasses lots of stuff, including
            //  java.net.SocketException, java.net.UnknownHostException,
            //  javax.net.ssl.SSLPeerUnverifiedException,
            //  org.apache.http.NoHttpResponseException,
            //  org.apache.http.client.ClientProtocolException,
            log.info("Error " + e + " connecting to " + imageURIString);
            errorResponse(request, response, "badurl");
            return;
        }

        try (InputStream is = connection.getInputStream()) {
            try {
                if (connection.getResponseCode() != HttpServletResponse.SC_OK) {
                    log.info("Unsuccessful return code " + connection.getResponseCode() + " from " + imageURIString);
                    errorResponse(request, response, "badurl");
                    return;
                }
                if (connection.getHeaderFieldInt(HttpHeaders.CONTENT_LENGTH, 0) > MAX_IMAGE_SIZE) {
                    log.info("Too large: " + imageURIString);
                    errorResponse(request, response, "badimage");
                    return;
                }
                // Assume we'll only handle image/* content types
                String contentType = connection.getContentType();
                if (contentType != null && !contentType.startsWith("image/")) {
                    log.info("Wrong content type " + contentType + ": " + imageURIString);
                    errorResponse(request, response, "badimage");
                    return;
                }

                log.info("Decoding " + imageURIString);
                processStream(is, request, response);
            } finally {
                consumeRemainder(is);
            }
        } catch (IOException ioe) {
            log.info("Error " + ioe + " processing " + imageURIString);
            errorResponse(request, response, "badurl");
        } finally {
            connection.disconnect();
        }

    }

    private static void consumeRemainder(InputStream is) {
        try {
            while (is.read(REMAINDER_BUFFER) > 0) {
                // don't care about value, or collision
            }
        } catch (IOException | IndexOutOfBoundsException ioe) {
            // sun.net.www.http.ChunkedInputStream.read is throwing IndexOutOfBoundsException
            // continue
        }
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        Collection<Part> parts;
        try {
            parts = request.getParts();
        } catch (IllegalStateException ise) {
            log.info("File upload was too large or invalid");
            errorResponse(request, response, "badimage");
            return;
        } catch (IOException ioe) {
            log.info(ioe.toString());
            errorResponse(request, response, "badimage");
            return;
        }
        Part fileUploadPart = null;
        for (Part part : parts) {
            if (part.getHeader(HttpHeaders.CONTENT_DISPOSITION) != null) {
                fileUploadPart = part;
                break;
            }
        }
        if (fileUploadPart == null) {
            log.info("File upload was not multipart");
            errorResponse(request, response, "badimage");
        } else {
            log.info("Decoding uploaded file " + fileUploadPart.getSubmittedFileName());
            try (InputStream is = fileUploadPart.getInputStream()) {
                processStream(is, request, response);
            }
        }
    }

    private static void processStream(InputStream is,
                                      HttpServletRequest request,
                                      HttpServletResponse response) throws ServletException, IOException {

        BufferedImage image;
        try {
            image = ImageIO.read(is);
        } catch (IOException | CMMException | IllegalArgumentException ioe) {
            log.info(ioe.toString());
            // Have seen these in some logs
            errorResponse(request, response, "badimage");
            return;
        }
        if (image == null) {
            errorResponse(request, response, "badimage");
            return;
        }
        try {
            int height = image.getHeight();
            int width = image.getWidth();
            if (height <= 1 || width <= 1 || height * width > MAX_PIXELS) {
                log.info("Dimensions out of bounds: " + width + 'x' + height);
                errorResponse(request, response, "badimage");
                return;
            }

            processImage(image, request, response);
        } finally {
            image.flush();
        }
    }

    private static void processImage(BufferedImage image,
                                     HttpServletRequest request,
                                     HttpServletResponse response) throws IOException, ServletException {

        LuminanceSource source = new BufferedImageLuminanceSource(image);
        BinaryBitmap bitmap = new BinaryBitmap(new GlobalHistogramBinarizer(source));
        Collection<Result> results = new ArrayList<>(1);

        try {

            Reader reader = new MultiFormatReader();
            ReaderException savedException = null;
            try {
                // Look for multiple barcodes
                MultipleBarcodeReader multiReader = new GenericMultipleBarcodeReader(reader);
                Result[] theResults = multiReader.decodeMultiple(bitmap, HINTS);
                if (theResults != null) {
                    results.addAll(Arrays.asList(theResults));
                }
            } catch (ReaderException re) {
                savedException = re;
            }

            if (results.isEmpty()) {
                try {
                    // Look for pure barcode
                    Result theResult = reader.decode(bitmap, HINTS_PURE);
                    if (theResult != null) {
                        results.add(theResult);
                    }
                } catch (ReaderException re) {
                    savedException = re;
                }
            }

            if (results.isEmpty()) {
                try {
                    // Look for normal barcode in photo
                    Result theResult = reader.decode(bitmap, HINTS);
                    if (theResult != null) {
                        results.add(theResult);
                    }
                } catch (ReaderException re) {
                    savedException = re;
                }
            }

            if (results.isEmpty()) {
                try {
                    // Try again with other binarizer
                    BinaryBitmap hybridBitmap = new BinaryBitmap(new HybridBinarizer(source));
                    Result theResult = reader.decode(hybridBitmap, HINTS);
                    if (theResult != null) {
                        results.add(theResult);
                    }
                } catch (ReaderException re) {
                    savedException = re;
                }
            }

            if (results.isEmpty()) {
                try {
                    throw savedException == null ? NotFoundException.getNotFoundInstance() : savedException;
                } catch (FormatException | ChecksumException e) {
                    log.info(e.toString());
                    errorResponse(request, response, "format");
                } catch (ReaderException e) { // Including NotFoundException
                    log.info(e.toString());
                    errorResponse(request, response, "notfound");
                }
                return;
            }

        } catch (RuntimeException re) {
            // Call out unexpected errors in the log clearly
            log.log(Level.WARNING, "Unexpected exception from library", re);
            throw new ServletException(re);
        }

        String fullParameter = request.getParameter("full");
        boolean minimalOutput = fullParameter != null && !Boolean.parseBoolean(fullParameter);
        if (minimalOutput) {
            response.setContentType(MediaType.PLAIN_TEXT_UTF_8.toString());
            response.setCharacterEncoding(StandardCharsets.UTF_8.name());
            try (Writer out = new OutputStreamWriter(response.getOutputStream(), StandardCharsets.UTF_8)) {
                for (Result result : results) {
                    out.write(result.getText());
                    out.write('\n');
                }
            }
        } else {
            if(results.size() > 0) {
                responseJSON(results, response);
            } else {
                if(ImageFilterCount == 0) {
                    ImageFilterCount++;
                    BufferedImage imageFilter = blurAndSharpImage(image);
                    processImage(imageFilter, request, response);
                } else {
                    responseJSON(results, response);
                }
            }
        }
    }

    private static int ImageFilterCount = 0;

    private static BufferedImage blurAndSharpImage(BufferedImage image) {
        GaussianFilter filter = new GaussianFilter(5);
        BufferedImage imageDest = filter.filter(image, null);
        SharpenFilter filterSharp = new SharpenFilter();
        imageDest = filterSharp.filter(imageDest, null);
        return imageDest;
    }

    private static void responseJSON(Collection<Result> results, HttpServletResponse response) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        int errno = 0;
        String text = null;
        if(results != null && results.size() > 0) {
            for (Result result : results) {
                ParsedResult parsedResult = ResultParser.parseResult(result);
                text = result.getText();

                if (text == null) {
                    errno = 1;
                    text = "";
                } else {
                    text = XmlEscapers.xmlContentEscaper().escape(text);
                }
            }
        } else {
            errno = 1;
            text = "解析失败";
        }
        QRRes qrRes = new QRRes(errno, text);
        response.setContentType(MediaType.JSON_UTF_8.toString());
        response.setCharacterEncoding(StandardCharsets.UTF_8.name());
        try (Writer out = new OutputStreamWriter(response.getOutputStream(), StandardCharsets.UTF_8)) {
            out.write(mapper.writeValueAsString(qrRes));
        }
    }


    private static void errorResponse(HttpServletRequest request,
                                      HttpServletResponse response,
                                      String key) throws ServletException, IOException {
        Locale locale = request.getLocale();
        if (locale == null) {
            locale = Locale.ENGLISH;
        }
        ResourceBundle bundle = ResourceBundle.getBundle("Strings", locale);
        String title = bundle.getString("response.error." + key + ".title");
        String text = bundle.getString("response.error." + key + ".text");
        QRRes qrRes = new QRRes(1, "err: " + key);
        ObjectMapper mapper = new ObjectMapper();
        response.setContentType(MediaType.JSON_UTF_8.toString());
        response.setCharacterEncoding(StandardCharsets.UTF_8.name());
        try (Writer out = new OutputStreamWriter(response.getOutputStream(), StandardCharsets.UTF_8)) {
            out.write(mapper.writeValueAsString(qrRes));
        }
    }

}
